Color photography.



F. E. NES.

coLoR PHOTOGRAPHY.

APPLICATION HLED 'DEC.5. 1912. 151739429, Patented Feb. 29, 1916.

FREDERIC E.` IVES, F WOODCLIFFE-ON-HUDSON, NEW JERSEY.

COLOR PHOTOGRAPHY.

Speciication of Letters Patent.

Application filed` December 5, 1912. Serial No. 735,064.

To all 'whom t may concern:

Be it known that4 I, FREDERIC EUGENE IvEs, a citizen of the United States, residing at Woodcliffe-on-Hudson, in the county of Bergen and State of New Jersey, have invented certain new and useful Improvements in Color Photography, of which the tography in two colors or in four colors, ity

is particularly intended for the three-color system, and is more especially directed to the red-sensitive and green-sensitive elements used therein.

An example of a plate-pack for the trichromatic or three-color system of colorphotography is illustrated in my Patent No. 927,244, of July 6, 1909, in which the redsensitive member or plate and the green-sensitive member or film are used pressed together in face contact, so that light rays passing from the objective of the camera through one of the transparent plates or films forms an image upon both of the closely contacting sensitive coatings thereof, thus making by a single exposure both a red and green photographic record, as required in the trichromatic process. Possibly the principles hereof would be applicable to contacting sensitive plates for other than the green and red light components of the image, and inl any case the plate-pack and arrangement of my Patent 980,961 of J an. 10, 1911 could be used for carrying out the present improvements.

I will endeavor to first state the condil tions in which has arisen the problem which I have met by the present invention. Photographic plates of the usual or silver bromid species can be prepared which are sensitive to green and not to red light, but it is not known how to prepare plates which will be sensitive to red light without being sensitive to some eXtent also to green light. For this reason the green-sensitive plate may be placed at the front and a red coating interposed between the two plates preferably on the surface of the green-sensitive plate, such coating being entirely supericial and extremely tenuous and water soluble, its

presence serving to prevent any substantial amount of green light from reaching the red-sensitive plate. The tenuous and temporary intermediate color coating is therefore one ofthe important requisites of a platepack such as the present improvements relate to. l

A further requirement for attaining perfection in such a plate-pack is that the redsensitive and green-sensitive plates shall have substantially identical gradation-giving qualities, and also density-giving qualities. This requirement cannot be insured, and it is rarely if ever possible when the red and green-sensitive plates are either manufactured in different factories or by different processes or even when made from different batches of emulsion in the same factory. In all those cases the qualities referred to usually vary quite measurably and materially, even as between emulsions made by the same formula at the same factory at different times. If the said requirement is attempted to be attained, or the said difliculty minimized, by taking ordinary sensitive plates, all from a single batch, and sensitizing half of them for red, and half of them for green, by the usual processes of bathing in suitable color-sensitizing dyes, practical satisfaction is impossible. Une reason for this fact is that no known sensitizing dyes which sensitize for green but not red will produce satisfactory plates of high speed and good keeping quality unless the dyes be added to the emulsion before the plates are coated, in which case the entire batch is vgreen-sensitive. Y

The principal part of the present improvement is that by which I have solved the difficulties and attained the requirements referred to, thus making available greensensitive and red-sensitive plates of u niformly and reliably equal qualities, which when placed face to face in a plate-pack will give results for color-photography of the highest satisfaction.

It must be appreciated that in the trichromatic system of color-photography, the process is one of analysis or separation 'of the three elemental color components of the image, and that consequently the perfection of the finished picture must depend upon the true preservation of the relative density and gradation of color in all -of the three component color records. Reference has been made principally to the red and Patented Feb. 29, 1916.

green components, and the third component is the blue, as to which the same difficulties do not pertain that exist in the cases of the red and green records. Thus in vmy prior patent No. 927,244, the blue-sensitive plate is placed at the front of the contacting red and green ones, and is comparatively tenuous and transparent, and eitherr uncolored or else colored in such way as to assist the proper formation of the red and green records.

Another feature of the present improvements comprises an improved method of obtaining a red su erficial colorl layer over the green-sensitive lm.

A third feature of the present improvements resides in Aperfecting the same through an opaque backing to the rearmost or red-sensitive plate, for the purposes and in the manner hereinafter set forth.

Having referred generally to the nature of the present improvements and the diiiiculties to be overcome, I will now refer more divide the same into two equal lots.

specifically to the preferred details in a method of carrying out the invention.

I have made the discovery that the isocyanin red-sensitizing dyes are extremely prepotent over the iuorescein green-sensitizing dyes, so much so in fact that plates made green-sensitive, for example, bythe addition of eosin to the emulsion may afterward be bathed for from under a minute to several minutes in a weak solution of pina- `chrome or of pinacyanol, or a mixture of the two, and thereby rendered red-sensitive; and that moreover red-sensitive plates so produced will be substantially identical in character with plates originally sensitized for the redrays-by the dye solutions last mentioned. By the employment of this disf covery I am enabled to secure a perfectly true and reliable set of plates, or a platepack, in which the red and green-sensitive plates will have the same qualities as to gradation and density. I prefer to proceed as follows. Commencing with a stock of green-sensitive plates all produced from the same emulsion containing a fluorescein green-sensitizing dye, or the equivalent, I One such lot of plates'will then be converted and rendered red-sensitive by treatment in the pinachrome or pinacyanol solution. The two elements of the pack are thus made alike in .age and speed, and in densityand gradation-giving qualities. When I s'ay color sensitizing or similar expression, it will be understood that I use the term in (the ordinary sense of giving to a sensitive plate a sensitiveness for a particular color or colors. The usual silver bromid plate may be described as a blue-sensitive plate for the reason that its original sensitiveness is such that the action of blue light very greatly preponderates over that of other colors.

ButJ if we treat the emulsion from which such a plate is made, or the plate itself, with certain dye-sensitizing agents for green, we in reality have a plate which is sensitive to both blue and green, but this is spoken of as a green-sensitive, 0r `more correctly, a greensensitized plate. A yellow screen eliminates the blue rays. If the green sensitized plate be converted according hereto, or red-sensitized, it will be sensitive to blue, green and red, the yellow and red screens, however, eliminating the blue and green rays. A red-sensitive plate, therefore, is not sensitive only for red, but is red-sensitized, permitting other colors tobe screened out, and enabling a true color-record of red rays to be secured. It should be further explained that a dye-sensitizer for green does not mean a green dye, as on the contrary it will probably have actually a minus-greenv color.

We now have the green-sensitive and redsensitive elements of the plate set or pack. Before assembling the plates in pairs for making up the plate-packs, the second lot will be .coated with the temporary screen coating for shutting out the green rays from the adJacent red-sensitive plate. Upon assemblage in pairs, the plate-packs are complete except so far as blue-sensitive plate is to be combined or employed in conjunction therewith.

I have above referred to the interposition upon the green-sensitive layer of a temporary or water-soluble dye coating, and this may be accomplished substantially by the method described in the aforesaid Patent 927,244, wherein an alcoholic solution of a suitable dye was flowed over the face of the plate. I prefer, however, the following described improved method by which I am enabled to obtain a more even and more deeply colored coating. This improvement consists in adding to the alcoholic dye solution before the plate is coated, some ether and also a very small amount of soluble gun cotton, after which the plate may be coated as before. With these additions the dye solution is of a practically more viscous character, but, what is very important, the ultimate thickness of the screen coating is not measurably added to. Specifically this part of my invention may be practised by taking,for example, four ounces of alcohol and two ounces of ether, saturated with a suitable dye such as fuchsin and adding one grain only of soluble gun cotton. By this formula is obtained an even and deeply colored, but quite superficial and immeasurably thin coating of water-soluble dye, in the use of which there will be probably not more than two thousandths of a grain of soluble gun cotton deposited upon each square inch of surface, leaving it freely water permeable.

We now have a plate-pack comprising a red-sensitive plate face to face with a green-sensitive plate which is red-coated. Such an assemblage is, especially upon the red-sensitive plate, susceptible to halation and also to injury by accidental exposure to light during handling, in use, and While making up the plate-packs. To prevent this and to perfect the plate-pack hereof to p the farthest degree, I provide the red-sensitive plates with a backing which is opaque to red light and which is in optical contact with the glass on the side opposite to the red-sensitive film. This efiiciently avoids the dangers referred to. There would be a difficulty in applying the backing after the plates are made red-sensitive, because they are unable to be exposed to much light of any kind, so that the necessary steps are hindered. I, however', propose herein to apply a backing by the aid of red illumination and at a time before the plates are made red-sensitive, which I find can be readily and satisfactorily accomplished if the present invention is employed. Light-excluding backings as are already known, such for example as colored collodion or gum containing lampblack, are not suitable because either the color or the substance itself is liable to be partly dissolved in the subsequent color-sensitizing solution, to the injury of the solution or the backing or both. I have overcome these difficulties and solved the problems stated, by employing for the backing of the red-sensitive plate a solution of asphaltum in benzol, in which a quantity of some suitable oil-soluble blue dye is dissolved. This solution is easily applied by a brush or by fiowing over the plate, and it dries very quickly, and when dry is insoluble in the color sensitizing bath which is made up of dye, water and alcohol. Blue is selected as a suitable minus-red color.

The complete formula may be: benZol 2S oz., bitumen 3 oz., Hoechst Companys oil soluble blue dye ll oz. With some qualities of bitumen it may be advantageous to replace 3 ozs. or 4 oZs. of the benzol with the same quantity of sulfuric ether.

I will now sum up completely the Steps involved in the present invention. wWe first produce a batch of green-sensitive plates preferably by use of the specific chemical or dye mentioned. Or we otherwise procure them, they being an ordinary commodity on the market. This batch of plates is then divided into two parts. Taking the first portion of the plates, they will first be coated at the back with the specific opaque coating referred to, which will be allowed to dry, and the plates will then be treated for rendering them red-sensitive, preferably by the use of the specific dyes hereinabove named, dissolved in a mixture of alcohol and water. In the meantime, the second portion of the plates which are already -to hereinabove.

green-sensitive, will be superficially coated with a temporary screen, such for example as the red colored screen specifically referred Having our two components we assemble them to form a platepack, and if desired combine a blue-sensitive plate therewith, for example by locating the same in front of the green-sensitive plate. By then securing the whole together, we have a unitary and easily handled platepack' which may be exposed in any desired manner. There for example may be a single exposure in an ordinary camera, as set forth in said prior Patent 927,244. After exposure the plates will be separated and developed and fixed. Finally the opaque backing upon the red-color record or negative can be easily removed by means of a piece of cloth moistened with benZol or turpentine, and the threel negatives or color-records are ready for the subsequent steps of making the prints or positives.

The chemical or dye which gives a plate sensitiveness for a given color may be termed a color-sensitizing agent, and the plate a dye-sensitized plate. The green-sensitizing agent already named, is preferably included in the original emulsion, and -is so used in the complete and preferred embodiment of this invention. When I refer to a sensitive plate, it is understood that as a carrier either a rigid glass plate or a flexible film is included.

As the physical arrangement of the components of the plate-pack hereof is susceptible of illustration, I have shown the same in the accompanying drawing, in which Fig. 1\shows a partial cross-section taken transversely of the plane of the plate-pack, with the several members or components slightly separated for clearness. Fig. 2 shows certain modifications.

In the figures the plate-pack 1 is shown as consisting of a plurality of members, namely the three members 2, 3 and 4, which beginning from the rear may be made up as follows.

The member 2 at the rear has the opaque back screen 5 of the composition and applied in the manner specified, upon the rear surface of the carrier or glass plate 6, at whose front face is the red-sensitive coating 7 produced as before described, by a conversion from green-sensitiveness.

The plate-pack member 3 may be made up, as shown in Fig. 1, of a red color-screen 8, of the composition previously stated, applied superficially upon the rear side of the green-sensitive coating 9, carried upon the carrier 10, which may be a thin transparent film as in prior patent 927,244.

The plate-pack member 4, if a third member be employed, may be made up of a yellow color-screen 11 superficially spread over a blue-sensitive coating 12 upon a carrier or glass plate 13, as shown, pro-vided that member 3 has a thin transparent film, and all are secured together as in patent 927 ,244. 'A

The three members 2, 3 and 4 constituting the plate-pack 1 may be secured together in the manner of my prior patent 927,244, or the red and green-sensitive plates may be at one point and the blue-sensitive at another point in such a camera as that of my prior patent 980,961, or the red and green plates might even be exposed at separated points, and the advantages of equal density and gradation are obtained. Obviously many variations in the specific make-up of the pack might be introduced; for example, the color-screen 8 might be, as shown in Fig. 2, upon the coating 7 rather than the coating 9, or the color-screen 11 might be as in F ig. 2 omitted from the Coating l2; or the carrier l0 might be of thin film or of glass at will, glass being preferred when the member 4 is omitted from the pack; or the described arrangement might be employed in connection with different colorsensitiveness for members 2 and 3.

It will thus be seen that I have described a plate-pack and process which accomplish the objects and` advantages hereinbefore recited, and other advantages will be apparent to those practising the improvements.

Since various features and details hereof may be altered without departing from the main principles involved, I do not wish to be limited thereto excepting as set forth in the appended claims.

What I claim and desire to obtain by Letters Patent is:

l. In the art of color photography the process of producing a set of color selection negatives which comprises the following steps: treating one of a batch of photographic plates which have been previously sensitized for a certain color to convert it to sensitiveness for a different color, and simultaneously exposing such converted plate and an unconverted plate from the same batch to the same light image.

2. In the art of color photography the process of producing a set`of color-selection negatives which comprises the following steps: treating one of a batch of photographic plates which have been previously sensitized for a certain color to convert it to sensitiveness for a different color, placing such converted plate face to face with an unconverted plate from the same batch, and

simultaneously exposing said plates to thesame light image.

3. In the art of color photography the process of producing a set of color selection negatives which comprises the following steps: treating one of a batch of photographic plates which have been previously sensitized for a certain color to convert it to sensitiveness for a different color, securing together in face to face contact such converted plate with an uncovered plate from the same batch, and simultaneously exposing the two plates through the support of one of them.

4. In the art of color photography the process of producing a set of color selection negatives which comprises the following steps: treating one of a batch of photographic plates which have been previously sensitized for a certain color to convert it to sensitiveness for a different color prior to combining it with an unconverted plate from the same batch, applying a temporary superficial color screen upon the sensitive coating of one of said two plates, subsequently combining said two plates in face to face contact, and thereafter simultaneously exposing the combined plates to the same light image.

5. In the art of color photography the process of producing a set of color selection negatives which comprises the following steps: treating one of a batch of green sensitized photographic plates to convert it to red sensitiveness, and simultaneously exposing such converted plate and an unconverted plate from the same batch to the same light image.

6. In the art of color photography the process of producing a set of color selection negatives which comprises the follow ing steps: treating one of a batch of green sensitized photographic plates to convert it to red sensitiveness, securing together in face to face contact such converted plate with an unconverted plate from the same batch, and simultaneously exposing the two plates through the support of one of them.

7. In the art of color photography the process of producing a set of color selection negatives which comprises the following steps: treating one of a batch of green sensitized photographic plates to convert it to red sensitiveness, placing such converted plate face to face with an unconverted plate from the same batch and with a transparent blue sensitive plate in front of both, and simultaneously exposing such three plates to the same light image.

8. In the art of color photography the process of producing a set of color selection negatives which comprises the following steps: preparing a batch of green sensitive photographic plates by incorporating a fluorescin dye in the emulsion, treating one of such batch of plates to convert it to red sensitiveness by a prepotent color-selecting agent, and simultaneously exposing such converted plate and an unconverted plate from the same batch to the same light image.

9. In the art of color photography the process of producing a set of color selectionv negatives which comprises the following steps: preparing a batch of green sensitive photographic plates by incorporating a fluorescin dye in the emulsion, treating one of such batch of plates to convert it to red sensitiveness by an isocyanin dye, and simultaneously exposing such converted plate and an unoonverted plate from the same batch to the same light image.

10. In the art of color photography the process of producing a set of color sele tion negatives which comprises the following steps: preparing a batch of green sensitive photographic plates by incorporating a f'luorescin dye in the emulsion, treating one of such batch of plates to convert it -to red sensitiveness by an isocyanin dye, and simultaneously exposing such converted plate and an unconverted plate from the same batch to the same light image while the two are in face to face contact.

11. In the art of color photography, the process of making a plate pack comprising the following steps: producing a plurality of differently color-sensitized photographic plates, coating the sensitive surface of one of them before assembling with a temporary superficial color layer suitable as a screen for one of the plates by spreading thereon a solution in alcohol and ether of dye stu and soluble cotton and assembling and securing together said plates into a plate pack.

12. In the art of color photography, the process of making a plate pack comprising the following steps: producing a plurality of differently color-sensitized photographic plates, coating the sensitive surface of one of them before assembling with a temporary superficial color layer suitable as a screen for one of the plates by spreading thereon a solution of substantially the proportions, alcohol el oz., ether 2 oz., soluble cotton 1 gr., and a suitable quantity of a dye color soluble in both alcohol and water and assembling and securing together said plates into a plate pack.

13. In the art of color`photography, the process of producing color-selection negatives comprising: preparing a plurality of green-sensitive plates by incorporation of the color sensitizing dye or agent in the emulsion, treating one thereof with a prepotent agent capable of rendering it redsensitive, coating a second one of such plates with a temporary red color layer or screen over its sensitive face, assembling a platepack comprising said first plate at the rear, said second plate in front of and in face contact with the first and a blue-sensitive plate in front of both, securing the whole together and simultaneously exposing them.

14. In the art of Vcolor photography, the process of makinga plate-pack comprising: preparing a batch of photographic plates sensitive to one color, coating the reverse of one1 thereof with an opaque, water-insoluble layer, converting such reversely coated plates to sensitiveness of a different color, and 'assembling in face contact said converted and an I-unconverted plate for exposure through .the .support of the unconverted plate.

15. In the art of color-photography, the process of making a plate-pack comprising: preparing a batch of green-sensitive photographic plates, coating the reverse of one thereof Iwith an opaque, water-insoluble layer, converting such reversely coated plate to red-sensitiveness, and assembling in face contact said converted andan unconverted plate for exposure through the support of the unconverted plate.

16. In the art of color photography the process of prodlfcing a `plate pack which comprises the following steps: coating with an opaque water insoluble layer upon its. reverse side one offa batch of photographic plates which have been previously green sensitized, treating said plate to convert it to red sensitiveness, assembling said plate in face contact with an unconverted plate from the same batch and applying a temporary superficial color screen upon the sensitive coating of one of said plates before assemblage.

17. In the art of color photography the process of producing a plate pack which comprises the following steps: coating with an opaque water insoluble layer upon its reverse side one of a batch of photographic plates which have been previously green sensitized, treating said plate to convert it to red sensltiveness, assembling said plate in face contact with anunconverted plate from the saine batch and applying a temporary superficial color screen upon the sensitive coating of one of said plates before assemblage; said opaque layer consisting of a mixture of asphaltum and an oil-soluble dye a'bsorptive of red light.

18. In the art of color-photography, the process of producing color-selection negatives comprising: preparing two greenesensitive plates by incorporation of the colorsensitizing agent in the emulsion, coating the first one thereof with an insoluble opaque coating over its back, treating the same thereafter with a prepotent agent capable of rendering it red-sensitive, introducing between said two plates a temporary red color layer or screen, assembling a platepack comprising said first plate at the rear, and the other plate at the front of and in face contact with the first, securing the assembled plates together, and simultaneously exposing them.

19. In the art of color-photography, the process of producing color-selection negatives comprising: preparing two green-sensitlve plates by lncorporatlon of a green sensit1z1ng fluorescin dye 1n the emulslon, coating the first one thereof with an insolublel opaque coating over its back, treating the same thereafter with an isocyanin dye for rendering it red sensitive, introducing between said two plates a temporary red color layer or screen, assembling a plate-pack comprising Said first plate at the rear, and the other plate at the front of and in face contact with the first, securing the assembled plates together and simultaneously exposing them.

20. In the art of color-photography, the process of producing color-selection negatives comprising: preparing a plurality of green-sensitive plates by .incorporation of the color agent in the emulsion, coating one thereof with an insoluble opaque coating over its back, treating the same thereafter with a prepotent agent capable of converting it from green-sensitive to lred-sensitive, coating a second one of such plates with a temporary red color layer or screen over'its sensitive face, assembling a plate-pack comprising said first plate at the rear, said second plate in front of and in Jface contact with the irst and a blue-sensitive plate in front of both, securing the assembled plates together and simultaneously exposing them.

2l. A plate-pack or plate-set for color photography comprising a plurality of differently color sensitized photographic plates secured together for simultaneous exposure, two of said plates being from the same batch -of color-sensitized plates, and one of said two plates having been converted to a different color sensitiveness.

22. A plate-pack or plate-set for color photography comprising a plurality of differently color sensitized photographic plates secured together for simultaneous exposure, two of said plates being from the same batch of green-sensitized plates, and one of said two plates having been converted to a redsensitiveness, and a third plate being bluesensitive.

23. A plate-pack or plate-set for color photography comprising a plurality of differently color sensitized photographic plates secured together for simultaneous exposure, two of said plates being from the same batch of color-sensitized plates, and one of said two plates having been converted to a different color sensitiveness, and suitable colorselective screens located between the sensitive layers.

24. A plate-pack or plate-set Jfor color photography comprising a plurality of differently color sensitized photographic plates secured together for simultaneous exposure, two'of said plates being from the same batch of green-sensitized plates, and one of said two plates having been converted to a redsensitiveness, and a third plate being bluesensitive, and suitable color-selective screens located between the sensitive layers.

In testimony whereof I affix my signature in presence of two witnesses.

FREDERIC E. IVES. Witnesses:

WILLIAM J. DoLA'N, DONALD CAMPBELL. 

